Chip packaging is one of the crucial processes in manufacturing a semiconductor device. The chip packaging process is started by the step of providing a lead frame structure with a chip carrier to support a semiconductor chip, wherein the chip carrier also severs as a bridge to electrically connect the semiconductor chip with other external electronic devices.
The semiconductor chip is first fixed on the carrier and then is electrically connected to the leads set on the lead frame structure by a welding step. Subsequently, a melted epoxy compound is then dispersed and molded to encapsulate the semiconductor die. The lead frame structure encapsulated by the molded epoxy compound is then trimmed to remove the spare materials (such as tie bars, a framework of the lead frame structured used to support the carrier, or the redundant molded epoxy compound) by a series punch steps, and the leads can be then bended into a predetermined shape.
However besides the physical nonconformity actually existed between the molded epoxy compound and the chip carrier, there are still problems to cause the molded epoxy compound and the chip carrier delaminated.
For example, since the melted epoxy compound is viscous, and the chip carrier could resist against the flow of the melted epoxy compound, when the greater carrier is applied, it is harder to disperse the epoxy compound uniformly to encapsulate semiconductor chip and the carrier. The molded epoxy compound cannot be integrated with the carrier well, and delaminating problems may occur.
To resolve the aforementioned problems, several penetrating openings are formed on the carrier to reduce the flowing resistance against the carrier, so as to enhance the dispersion of the melted epoxy compound. However applying the penetrating openings cannot thoroughly resolve the delaminating problems, but otherwise reduces the supporting force against the flowing epoxy molding compound and results in the carrier bended.
It is desirable to provide an improved lead frame structure with simple structure and less cost to resolve the lamination problems without reducing the supporting force against the flowing epoxy molding compound during the chip encapsulating steps.